FIG 2.

Anti-Pfs25 IgG titers in mice vaccinated with alga-produced Pfs25 antigen in combination with human-compatible adjuvants. Ten mice per group were vaccinated with or without affinity-purified alga-produced Pfs25 antigens mixed with AL007 (2 mg/ml alum), AL019 (0.5 mg/ml alum plus GLA), EM081 (squalene–oil-in-water emulsion), and EM082 (squalene–oil-in-water emulsion plus GLA). Each group of mice was vaccinated with the initial dose of 20 μg alga-rPfs25 antigen plus adjuvant, followed by 3 injections of 10 μg of antigen at 3-week intervals. The vaccinated mice were bled 2 weeks after the final immunization, sera were pooled, and anti-Pfs25 IgG titers were determined by ELISA. Titers for rPfs25 plus adjuvants are reported after subtracting signals obtained using serum from each respective adjuvant-alone group. Pfs25 monoclonal antibody secreting hybridoma (4B7) was obtained from MR4 and cultured in vitro, and the MAb was purified and used as a positive control in this assay at a stock solution concentration of 1 mg/ml. Pooled prebleed mouse sera were used as negative control. ELISA plates were coated with alga-Pfs25 antigens (100 ng/well) in sodium bicarbonate buffer, pH 9.6, and serial serum dilutions (1/500 to 1/64,000) were used to determine titers.